18-5007 Sierra Tune Up Kit Replaces Mercury 398-174 and 398-693

18-5007 SIERRA TUNE UP KIT Comprehensive maintenance package engineered for Mercury engine performance optimization. This OEM-equivalent kit replaces Mercury parts 398-174 and 398-693, consolidating essential tune-up components into a single convenient solution. Includes precision-engineered spark plugs, ignition components, and fuel system elements calibrated for optimal combustion efficiency and engine responsiveness. Designed to restore peak performance on aging engines and maintain reliability on newer installations. Marine-grade materials withstand saltwater exposure and thermal cycling. Ideal for seasonal maintenance, performance restoration, or complete engine service on Mercury-equipped vessels. Simplifies routine upkeep and ensures consistent engine operation in demanding marine conditions.